High speed recoilless chisel device



Sept. 3, 1968 YUKIO IMAMURA HIGH SPEED RECOILLESS CHISEL DEVICE FiledDec. 15,.1965

' INVENTOR. M2, J

United States Patent "ice P 1 3,399,441 HIGH-SPEED RECOILLESS CHISELDEVICE .Yukio Imamura, 1156-1, Renjaku, Fujinomiya, Shizuoka Prefecture,Japan v Filed Dec. 13, 1965, Ser. No. 513,358

.. l. 1 Claim. (Cl. 29-81) ABSTRACT F THE DISCLOSURE A primary object ofthe present invention is to provide a highspeed recoilless chisel devicein which an actuating member is caused to move reciprocally in thevertical direction withinthe casingv of the device so as to causechopping tools movably disposed in the actuating member to initiate tomove reciprocally in the vertical direction within an operation spacedefined b the actuating member and after the initial movement thechopping tools then continue to move reciprocally only by their force ofinertia.

1 *Another'obje'ct of the present invention is to provide an improvedhigh speed recoilless chisel device of the above type which can beutilized for various industrial purposes such as scrapping-off of slagson weldments, chopping-off of beads on weldments, rough finish, breakingand boring of concrete constructions, removing of casting fins,'impacttransmission and the like.

"According to the present invention, there is provided an improvedhigh-speed recoilless chisel device which can "effectively perform theabove purposes and in which 'an actuating member is actuated so as tomove reciprocally in the vertical direction within the casing of thedevice and-the reciprocal movement of the actuating member'is'thentransmitted to chopping tools disposed within anoperating space definedby the actuating member so as to develop aforce of inertia in the toolswhich will "then cause the chopping tools to move reciprocally towardand away from a work on which a desired operation is'to be'performed.The above and other objects, features and attendant advantages of thepresent invention will become apparent to those skilled in the art froma reading of the following detailed explanation" of two preferredembodiments thereof in conjunction with the accompanying drawings.

- In the drawings:

FIG. 1 is a fragmentary vertical sectional view of a first, embodimentof chisel device constructed in accordance with the present invention;

,-.FIG-. 2 is a cross sectional view substantially taken along the lineII- II of FIG. 1;

FIG. 3 is a cross sectional view substantially taken along the lineIIIIII of FIG. 1; and

FIG. 4 is a fragmentary view showing one of chopping tools employed insaid chisel device illustrated in FIG. 1.

Now referring to the figures of the drawings, especially to FIG. 1 inwhich 'a first preferred form of chisel device according to the presentinvention is shown. As seen from this figure, the first embodiment ofchisel device generally comprises a hollow main body or casing 1 whichhouses various elements constituting the device and has a cover 2 whichis removably secured to the top of the casing in the conventionalmanner. An electric motor 3 is mounted within the cover 2 in theconventional manner and one end of the motor has an 3,399,441 PatentedSept. 3, 1968 electric cord attached thereto (not shown) which isadapted to be connected to a suitable electric source (not shown). Theother end of the motor 3 has an output shaft 4 extending downwardly andhaving a reduced diameter portion 4' provided with splines-The reduceddiameter portion 4' of the motor output shaft 4 extends into the casing1 and is journalled in bearings 5 disposed in an opening 6 formed in thetop wall 1 of the casing 1. The larger diameter portion of the outputshaft 4 has a cooling fan 7 disposed around theperiphery thereof. A gearframe or box 8 is secured to the casing 1 by any suitable means such asbolts and the, gear box houses a gear 9 which engages with the reduceddiameter splined lower portion 4' of the motor shaft 4. The gear 9 isrigidly mounted .on a rotational shaft 10 whose reduced diameter one endis loosely received in a sleeve member 11 disposed within a recessformed. on the. underside of the top wall 1' of the casing 1 adjacent tothe opening 6 which receives the bearings 5 which journal the splinedlowerportion 4' of the motor shaft 4 and the other end of the shaft 10is journalled in bearings 12 disposed within an opening 13 formed on thebottom wall 8' of the gear box 8. The intermediate portion of the shaft10 between the opposite ends thereof is threaded for receiving 'abearing retainer 14 which has an inner thread and serves to hold thebearings 12 in position. A circular mounting member 15 is rigidlysecured to the lower journalled end of the rotational shaft 10 by anysuitable means such as pins (not shown) for rotational movementtherewith. The top surface of the mounting member 15 lies in the horizonwhilst the undersurface thereof is slanted with respect to the horizonas indicated with a. The mounting member 15 has a downwardly extendinghollow boss or shaft 16 the axis of which is .eccentric with respect toor deviated from the axis of the mounting member 15 for the reason to bedescribed hereinafter and has an inner thread. A swinging member 17which comprises a hollow cylin drical body 17' and .a laterallyprojecting extension or arm 17" having a spherical tip end 17" isswingingly mounted on the eccentric shaft 16 of the mounting member 15for a cranking movement with bearings 18 interposed between the shaft 16and the hollow body 17'. The bearings 18 are held in position byscrewing a head bolt 19 into the threaded bore of the shaft 16 with awasher 20 interposed between the lower end of the shaft 16 and the headof the bolt 19. The swinging member 17 is adapted to swing about theeccentric shaft 16 in a cranking movement while sliding along theslanted undersurface a of the mounting member 15. A stationary hollowcylindrical member 21 having an opening 21 on one side is provided belowthe gear box 8 in a position for receiving the substantial portion ofthe laterally projecting arm 17" of the swinging member 17 and the sizeof the opening 21 is sufliciently large to allow the cranking movementof the swinging member 17. The lower portion of the stationary hollowcylindrical member 21 is externally threaded for the purpose to beexplained hereinafter. A vertically slidable hollow cylindricalactuating member 22 is received within the outer stationary cylindricalmember 21 and has a plurality of air bores 22' in its periphery. Theactuating member 22 has a circular intermediate partition 22" whichextends across the diameter of the member 22 and defines an operationspace or chamber b in cooperation with the top wall 22" of the actuatingmember and into which the spherical end 17" 0f the 'arm 17" of theswinging member 17 extends. The size of the operation space b is soselected that the spherical arm end 17 may freely move therein, but theend 17" may also maintain its slide contact relation with the innersurface of the top wall 22" and the inner surface of the intermediate 3partition 22" and the space b is outwardly flared at one end as definedby the beveled one ends of both the wall and partition. The innersurface of the lower portion of the act-uating member 22 is providedwith an annular recess and a solid cylindrical guide member 23 having aplurality of through bores 23 is received within the recess c whereby aspace or chamber d is defined between the intermediate partition 22" ofthe member 22 and the guide member 23. The size of the bores 23' isslightly larger than the diameter of one of chopping tools of whichexplanation will be made hereinafter so that the tools may freely movereciprocally in the vertical direction while being restrained frominclining during the operation. The guide member 23 may be held inposition by any suitable means such as an annular ring 24 asillustrated. A plurality of chopping tools which are illustrated in theform of nail 25 extend through the respective bores 23' of the guidemember 23 and these nails 25 are disposed with their heads abuttingagainst the top surface of the guide member 23 as shown in FIG. 1 whenthey are in their inoperative position. A reversed frusto-conical shapedhollow end member 26 having a thread on the inner surface of the upperlarger diameter portion thereof is screwed onto the externally threadedlower portion of the stationary cylindrical member 21. Thus, it will beunderstood that the frusto-conical end member 26 serves as aconstriction and guide means for the group of chopping tools 25 inaddition to its function as the tip end portion of the casing 1.

In the operation of the above mentioned chisel device by the presentinvention as described above, the motor 3 is first actuated in theconventional manner so as to rotate its output shaft 4. The rotationalmovement of the shaft 4 is transmitted through the gear 9 which is inengagement with the shaft 4 to the mounting member which in turntransmits its rotational movement to the eccentric shaft 16 which isintegral therewith. The thus actuated eccentric shaft 16 causes theswinging member 17 to swing in a cranking movement while sliding alongthe slanted undersurface a of the mounting member 15 and accordingly,the spherical arm end 17" is caused to move upwardly and downwardly insliding contact with the inner surfaces of the top wall 22" andintermediate partition 22" of the actuating member 22 so as to effectthe reciprocally vertical movement of the actuating member 22. Suchreciprocal movement of the actuating member 22 in turn effects thevertical reciprocal movement of the group of chopping tools 25 at a highspeed and the thus actuated chopping tools are caused to strike againsta work on which a desired operation is to be performed. In this way,after the actuating member 22 has once been forced to descend at a highspeed with a high impact applied thereon by the rotating swinging member17 so as to transmit the thus applied high impact onto the choppingtools 25 by the latters heads and thereby the tools have in turndescended at the same high speed toward the work to transmit the highimpact onto the work, the actuating member 22 is rapidly forced toascend because the inner surface of the intermediate partition 22" ofthe actuating member is struck by the heads of the chopping tools 25which are rapidly ascending by the repelling force which has beengenerated due to the striking of the chopping tools 25 against the workwith the high impact. When the chopping tools 25 are operated in themanner as mentioned just above, their cyclic striking etficiency isaugmented because their ascending movement after their descent forstriking against the work is C I. 3 abruptly halted by the intermediatepartition 22" of the actuating member 22 the ascending movement of whichis also abruptly halted byithe rotating swinging member 17. The abovecycle of operation of the actuating member 22 and chopping tools 25 isallowed to continue so long as the electric motor 3 is rotating andaccordingly, the swinging member 17 is rotated thereby. However, in thiscase, the energy which has been generated due to the operation of thechopping tools .25 in the manner mentioned above can be effectivelyprevented from being transmitted to the hands-of the operator becausethe swinging member 17 which is rotating at high speed prevents suchtransmittance of energy and therefore, the degree of fatigue on the partof an operator may be substantially less as compared with thatexperienced with the conventional chisel devices. Furthermore, thenovel'chisel device is far more safer than the conventional chiseldevices because no kickback. takes place during the operation of thenovel chisel device which have frequently taken place on theconventional chisel devices.

What I claim is: a t

1. A high speed recoilless chisel. device comprising, in combination, ahollow casing, an electric motor mounted in said casing and having ageared drive shaft, a transmission gear drivingly engaging said shaftandhaving a second shaft on which said transmission gear is rigidly mountedfor rotational movement therewith, a mounting member rigidly secured toone end of said second shaft of the transmission gear and having anundersurface obliquely disposed to the axis of said second shaft and aneccentric stud extending downwardly from said oblique surface, aswinging member mounted on said stud of the mounting member for crankingmovement around said eccentric stud and having a laterally extending armhaving a spherical tip end, a stationary hollow cylindrical memberafiixed to said casing having an opening in its periphery for slidablyreceiving said arm of the swinging member, an axially movable hollowcylindrical actuating member disposed within said stationary cylindricalmember for sliding movement therein having an operating chamber forreceiving said spherical tip end of the swinging member 'arm whichreciprocates said actuating member as said swinging member swings in acranking movement, a guide member disposed within said actuatingmemberand having a plurality of bores extending therethrough, a toolslidably extending through each of said bores of the guide member andadapted to move reciprocally within said actuating member under inertiaforces and a'hollow end extension member secured to the lower end ofsaid casing through which said tools extend for guiding and c0nstrictingsaid tools.

References Cited UNITED STATES PATENTS 2,455,626 12/ l948 Traut 74-452,491,624 12/1949 Shaff 74-60 2,824,455 2/ 1958 Ristow et al 74-603,150,888 9/1964 Parker 29-81 3,343,246 9/1967 Kelley et al. 2981 OTHERREFERENCES German printed application, Renz, 1,027,039, March 1958.

WALTER A. SCHEEL, Primary Examiner.

J. M. NEARY, Assistant Examiner.

